Two explosions have ripped through Russia's main natural gas supply pipeline to Armenia and Georgia, halting supplies to the two countries.
The blasts occurred close to the border with Georgia early on Sunday morning.
A spokesman for Russia's emergency situations ministry said officials were examining the possibility of sabotage, although it was too early to say.
Georgian energy officials say there are 24 hours worth of gas in the pipeline, as cold weather grips the country.
The daytime temperature in Tbilisi on Sunday was -7C, well below the January average, and Georgia relies on Russian natural gas for most of its heating.
The explosions occurred on the main branch and a reserve branch of the Mozdok-Tbilisi pipeline in the Russian border region of North Ossetia at around 0300 local time (0000 GMT).
Reports say it could take several days to restore supplies, due to the site's remoteness and poor weather conditions.
Georgia is holding talks aimed at securing supplies from Azerbaijan and Iran, but this could also take several days, said Georgian Deputy Energy Minister Aleko Khetagurov.
Russia also supplies gas through Georgia to Armenia, which in turn sends some electricity back to Georgia.
Gas prices to the two countries were doubled in January to $110 per 1,000 cubic metres, as part of a series of recent price hikes for former Soviet countries.
Armenian President Robert Kocharyan is expected to discuss the gas situation in a meeting with Russian President Vladimir Putin, during a visit to Moscow which starts on Sunday.